I would do a little research before buying...
Here is a post I wrote just a couple of hours ago to someone with a similar questions
Do you know a good mechanic?
Have you researched the 6.0 problems/fixes?
Are you going to gamble and fix problems as they come or are you going to try and prevent problems?
I love my 6.0 and I hated my 7.3... If i was to do it over again I would look for a 6.0 with problems, cheaper, but still in good shape. I would take the money I saved on the discount/problems and invest it in all the things that make it bulletproof/gorilla proof.
Example... I saw a ccsb 4x4 lariat 6.0 on craigslist this week for $6500 with blown head gaskets. I would buy it, pull the motor, invest about $8000 in fixing all hte problems and have about $14,500 in a bulletproof 6.0
You could buy the truck for $24,000 and still end up having problems and then have to slowly invest the same amount of money into your low mileage newer 6.0 because a lot of them have the same problems.
Take your time, do your research, search the forums and don't be in a hurry to buy anything. Also don't trust what anyone is saying about the truck you are buying. Learn how to investigate it yourself. I just bought a "bulletproof" 6.0 with ARP head studs, bulletproof egr, new oil cooler, etc... well after a week of owning it I found out it had blown head gaskets because of the crappy victor reinz head gaskets and a bad head job... just I would not pay more because you think you will have less problems.
I know that I am new to posting on this forum but I have been reading the forums for years... and I HATE seeing someone get on here and there first post always says something like "dang I wish I would have known all this before I bought my 6.0" or "why didn't I find this forum sooner before investing $5000 in the same old OEM problems" etc... I feel bad for those people, not for any other reason other than I have been there and it sucks